1. Field of the Invention
The present invention relates generally to a device for controlling the opening of a cam operated cylinder head valve, and more specifically to a device positioned between the rotating cam and the cylinder valve for opening the cylinder valve by an amount progressively proportional to the amount of lift provided by the cam lobe.
2. Description of the Prior Art
Various devices have been used in internal combustion engines for controlling the amount of opening of a cylinder valve with respect to the amount of lift provided by the rotating camshaft, generally as a function of engine oil pressure, which in turn, is a function of engine rotational speed (R.P.M.). The theory behind this type of hydraulic valve lifter is to use "incompressible" engine oil to control the amount of lift of the lifter with respect to the cam lobe. Of course, due to the shape of a cam lobe, the point in time (degree of rotation of the camshaft) may also be regulated to control the "timing" at which the cylinder valve opens and closes.
However, such devices have not been able to compensate for the necessary abrupt transition between the camshaft concentric surface and cam lobe. Such abrupt transitions have resulted in unnecessary impact between the cylinder valve and valve seat, sometimes accompanied by valve "bounce", contributing to impaired engine performance.